Conventionally, there has been publicly known a technique of a turbocharger provided in an internal combustion engine. Such a technique of a turbocharger is disclosed, for example, in Japanese Patent Application Laid-Open No. H9-310620.
The turbocharger rotatably supports a shaft, by a bearing housing, connecting a turbine driven by exhaust gas and a compressor for compressing intake air. Further, the turbocharger includes a sliding bearing interposed between the bearing housing and the shaft, and is configured such that the shaft is rotated smoothly.
However, in the case where the sliding bearing is used in a portion rotating at high speed like the shaft of the turbocharger, since clearances between the bearing housing and the sliding bearing and between the sliding bearing and the shaft are narrow, whirl vibration may occur in the portion. Further, in the case where the whirl vibration occurs, noise (abnormal sound) caused by the whirl vibration may occur.